An intraluminal prosthesis is a medical device used in the treatment of diseased blood vessels. An intraluminal prosthesis is typically used to repair, replace, or otherwise correct a diseased or damaged blood vessel. An artery or vein may be diseased in a variety of different ways. The prosthesis may therefore be used to prevent or treat a wide variety of defects such as stenosis of the vessel, thrombosis, occlusion or an aneurysm.
One type of intraluminal prosthesis used in the repair of diseases in various body vessels is a stent. A stent is a generally longitudinal tubular device formed of biocompatible material which is useful to open and support various lumens in the body. For example, stents may be used in the vascular system, urogenital tract and bile duct, as well as in a variety of other applications in the body. Endovascular stents have become widely used for the treatment of stenosis, strictures and aneurysms in various blood vessels. These devices are implanted within the vessel to open and/or reinforce collapsing or partially occluded sections of the vessel.
Stents generally include an open flexible configuration. This configuration allows the stent to be inserted through curved vessels. Furthermore, this configuration allows the stent to be configured in a radially compressed state for intraluminal catheter implantation. Once properly positioned adjacent the damaged vessel, the stent is radially expanded so as to support and reinforce the vessel. Radial expansion of the stent may be accomplished by inflation of a balloon attached to the catheter or the stent may be of the self-expanding variety which will radially expand once deployed. Structures which have been used as intraluminal vascular grafts have included coiled stainless steel springs; helically wound coil springs manufactured from a heat-sensitive material; and expanding stainless steel stents formed of stainless steel wire in a zig-zag pattern. Examples of various stent configurations are shown in U.S. Pat. No. 4,503,569 to Dotter; U.S. Pat. No. 4,733,665 to Palmaz; U.S. Pat. No. 4,856,561 to Hillstead; U.S. Pat. No. 4,580,568 to Gianturco; U.S. Pat. No. 4,732,152 to Wallsten; U.S. Pat. No. 5,395,390 to Simon et al. and U.S. Pat. No. 4,886,062 to Wiktor, all of whose contents are incorporated herein by reference.
A graft is another commonly known type of intraluminal prosthesis which is used to repair and replace various body vessels. A graft provides a lumen through which blood may flow. Moreover, a graft is often configured as being generally impermeable to blood to inhibit substantial leakage of blood therethrough. Grafts are typically hollow tubular devices that may be formed of a variety of materials, including textile and non-textile materials.
A stent and a graft may be combined into a stent-graft endoprosthesis to combine the features thereof. It is often desirable to use a thin-walled graft in the stent-graft endoprosthesis to minimize the profile of the endoprosthesis and to maximize the flow of blood through the endoprosthesis. In such cases non-textile materials, such as polymeric tubes or sheets, are often used. Expanded polytetrafluoroethylene or e-PTFE is one common polymeric material used as the graft portion of a stent-graft endoprosthesis. Expanded polytetrafluoroethylene grafts, however, are subject to tearing or puncturing, leaving the stent-graft endoprosthesis prone to leakage of blood therethrough. Furthermore, expanded polytetrafluoroethylene grafts are susceptible to kinking, which is also undesirable because it may lead to poor blood flow patterns.
Thus, there is a need for a polymeric graft for use in a stent-graft endoprosthesis that has improved mechanical properties to resist tearing or puncturing.